Ultra-high salt-resistant eggplant carbon evaporator: Evaporation performance and salt-resistance mechanism

The coupling of salt resistance and high evaporation performance for sustainable clean water production has long posed a challenge in high-salinity water evaporation. Herein, biomass eggplant carbon (EC) aerogel was developed combining the advantages of ultra-high salt resistance and high evaporation rates. The EC aerogel achieved an evaporation rate of 1.60 kg·m −2 ·h −1 when evaporating 25 wt% saline water over a duration of 600 min under one sun irradiation, demonstrating both high evaporation performance and outstanding salt resistance. The experimental and numerical simulation results confirmed the ultra-high salt resistance attributed to: (1) the rapid water transport rates (21 mm·s −1 within 1 s and 7.5 mm·s −1 within 5 s) induced by the strong capillary action, which maintained the salt concentration at a lower level on the aerogel surface, (2) the fast water backflow capacity carried away the concentrated salt solution close to the EC surface to bulk water in a timely manner, and (3) the highly porous, interconnected millimeter-sized holes in the aerogel shortened the ion transport path, thereby enhancing the water supply/backflow properties. The rapid water replenishment and fast water backflow capacities synergistically kept the saline water on the EC surface below the salt precipitation concentration, endowing the EC aerogel with superior salt-resistant properties. This study contributes to a deeper understanding of high salt-resistant properties and inspires materials engineering with rapid water supply/backflow, as well as their practical applications in clean water generation from hypersaline water.